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J Type Overdrive


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My Vitesse-based car had a D to J type overdrive conversion way back in 2001 and was standing for at least 4 years before I acquired it last year.

The switches have been renewed but not the solenoid. The overdrive doesn't activate when switched on.

Is the solenoid the likely cause of the fault or is there a chance that the overdrive will free itself up in a few hundred miles after being left unused for so long?

Not eager to drop the engine etc.

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With the ignition on, only, can you hear the clicking ??

Is the oil level correct and not too low and is the correct oil in there - if uncertain it will be worth changing for new.

Canley Classics do an excellent article covering the A / D / J type O/D's - well worth reading.

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When I first converted my first Vitesse to OD, with a D-type box from a local scrap yard (those were the days!) it did absolutely nothing beyond making a clunk. However, I was combining the test drive with an errand so I completed my 4 mile outbound trip. On the way home, I left the overdrive turned on but non-operational. About half way home, it suddenly engaged and proceeded to work fine for the rest of that gearbox's (rather short) life.

I don't actually recall whether it was the first or the second time I took Toby out after his 30-year rebuild that I got him into overdrive. It was definitely at least a little slow the first time I tried, and that was with a "new" rebuilt J-type box from Canley... that had been sat on the rolling chassis and later the progressively built-up car for over a decade.

It's definitely worth checking for the clunk and the oil level but if you've not driven it enough to get properly warm yet then it may well just be a bit sticky.

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I had a J type solenoid play up when we got the 2000, 

Needs  a thin 1"af spanner to remove it, 

The body has O rings to seal its ports but in the end is a small 10mm circlip, remove this and shake the inner spool valve  piston out

This also  has O rings not often mentioned , this little sod needs to be free to move,  if you shake the sol you should hear it move

Whilst the sol is not overly tight to unscrew do not use grips on the body , it is likely to seperate and be scrap

If this inner spool is stiff or the seals fail you can get some very involuntary operation , like a mind of its own or just inoperative

You dont  need to drain oil to remove the solenoid, ,  , you might get a cup full .( I think )

J type dont need a relay but check its working if you happen to have one fitted

And the notorius fractured wires if the gear knob switch is used


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  • 1 month later...
13 hours ago, RayHutch said:

Had the overdrive checked and the problem was lack of oil. It’s been topped up and now works a treat !

I was too late to post that hint (although the guys have it well covered already above!)

It's always the first thing to check; mine was intermittent, and I blamed the electrics, until a small - and it was a surprisingly small amount - of top-up oil had it working perfectly again.

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